Antenna systems



Sept. 4, 1956 F. T. WIMBERLY ANTENNA SYSTEMS 2 Sheets-Sheet 1 Filed June 25, V1952 Sept. 4, 1956 F. T, WIMBERLY ANTENNA SYSTEMS 2 Sheets-Sheet 2 Filed June 25, 1952 N wbk n ko m w.

h. @bk PPI@ khl W//// \m /f/ Nm. NM1 ww Olm.. Wm. WIM .Wm

Q R. Q Q. wv MUPN P United States Patent ANTENNA SYSTEMS Floyd T. Wimberly, Watertown, Mass., assigner to Raytheon Manufacturing Company, Newton, Mass., a corporation of Delaware Application June 25, 1952, Serial No. 295,423 16 Claims. (Cl. 343-100) This invention relates to systems for radiating and receiving electrical energy, and more particularly to an antenna system useful for radar purposes.

In radar systems of the frequency-modulated or continuous-wave type, a portion of the transmitted signal is fed directly into the receiver to beat with the returning echo wave, thereby producing a signal indicative of range or speed according to well-known practice.

Prior to this invention it has been diicult to adequately isolate the transmitting wave from the receiving Wave so that only a small amount of the transmitted wave was fed directly to the receiver. This invention discloses an antenna system wherein the transmitting antenna is isolated from the receiving antenna to a greater degree than was heretofore possible. Brieliy, this is accomplished by using radiating horns whose large ends are connected to a ground plane. The radiation patterns of the horns are oriented in a direction perpendicular to the ground plane, and the apertures in the ground plane with which the large ends of the horns register are spaced apart by a plurality of wave lengths.

This invention further discloses an antennastructure which is structurally rigid whereby microphonics, which would cause modulation of the portion of the signals fed from the transmitting antenna to the receiving antenna, are substantially eliminated. Briefly, this is accomplished by rigidly attaching the horns to the ground plane, and by connecting a rigid member between the horns at a point remote from the ground plane. More specifically, the rigid member is connected to the horns at the points of coupling of the horns to the signal translation means by which the transmitted signal is coupled into the transmitting horn and the received signal is picked up from the receiving horn. In order to insure a predetermined amount of signal energy being fed directly from the transmitting horn lto the receiving horn, a signal channel is coupled from the transmitting horn to the receiving horn. In order to insure rigidity of this coupling path to prevent modulation of this energy, the channel is made part of the rigid member, more speciicaliy being a coaxial line inside the rigid mem-ber, said coaxial line having a tilling of lossy material whereby the desired degree of attenuation of the signal fed directly from the transmitting horn to the receiving horn may be accurately maintained.

This invention further ,discloses a system wherein all the high-frequency energy channels are positioned in one unit, thereby eliminating the need for high-frequency cables to connect one unit with another, or the use of exible or rotating high-frequency joints to Aallow the movement of one unit with respect to another. Speciiically, the high-frequency unit is the antenna system with the source of high-frequency energy, for example, a.

magnetron, resiliently mounted on the antenna unit. The receiver mixer is also mounted on the antenna unit such that the output of the receiver, which is a relatively low frequency intelligence signal, may be conducted from the BCC antenna to any other unit, for example, an indicator unit, oy means of conventional wiring techniques.

Other and further objects and advantages of this invention will be apparent as the description thereof progresses, reference being had to the accompanying drawings, wherein:

Fig. l illustrates a partially broken-away perspective view of an antenna system embodying this invention;

Fig. 2 illustrates a front elevation view of the device shown in Fig. 1;

Fig. 3 illustrates a longitudinal cross-sectional View of the device shown in Figs. l and 2 taken along line 3 3 of Fig. 2;

Fig. 4 illustrates an enlarged view of a detail of the device shown in Figs. 1, 2, and 3;

Fig. 5 illustrates a block diagram of a frequencymodulation or Doppler radar system embodying the antenna system of this invention;

Fig. 6 illustrates a block diagram of a pulse echo radar system embodying the antenna system o-f this invention; and

Fig. 7 illustrates an installation of the antenna system of this invention adapted for rotation about a vertical axis as would be required for a conventional marine navigational radar system.

Referring now to Figs. l, 2, and 3, there is illustrated a ground plane 10 comprising a flat metallic member. Rigidly connected to the ground plane 10 is a pair of wave guide horns 11 and 12, respectively. Horns 11 and 12 have their large ends flared in a direction perpendicular to a line intersecting and perpendicular to the longitudinal axes of the horns, said longitudinal axes being oriented in a direction perpendicular to the ground plane 10. By this structure, the horns 11 and 12 are substantially matched to the free space occurring outside the horns when the horns are excited in the TEoi mode with the electrostatic lines perpendicular to the plane containing the axes of the ho-rns.

The horn 12 is used as a transmitter horn and is excited by a probe 13 extending into the horn at a point in the region adjacent the small end of the horn which is closed by a conductive plate as at 14. The probe 13 is positioned parallel to the electrostatic lines of the waves in the guide i2, but does not extend entirely across the guide 12. The probe 13 is surrounded by a sheath 15 of dielectric material Which extends entirely across the guide and out through one wall thereof surrounding the probe 13. Where the sheath 15 and probe 13 extend out through the wall of the guide 12, they are attached to a conventional coaxial line fitting 16, whereby power is fed into the horn 13. The axis of probe 13 does not intersect the axis of the horn but is offset, by an amount determined by the impedance of the coaxial line coupled to the probe, to produce a good impedance match between the coaxial line and the horn. Similarly, the probe 13 is spaced from the shorting member 14, closing the small end of the guide 13, for impedance matching purposes.

A coaxial line illustrated diagrammatically at 17 connects the coaxial iitting coupled to probe 13 with the coaxial output 18 of a magnetron oscillator 19 which is resiliently mounted in the space between the horns 11 and 12. The magnetron 19 is shown by way of example only and any desired source of high-frequency energy, such as a klystron or high-frequency vacuumy tube triode oscillator, could be used. As is illustrated here, the magnetron 19 is rigidly clamped to a support member 20 by means of straps 21. A connecting plug 22 is attached to support member 20 so that the magnetron 19 may be readily removed from the device by simply disconnecting the coaxial coupling 18, removing the straps 21, and pulling the magnetron 19 out of the plug 22. All of the desired low frequency electrical connections to the magnetron ground plane 10. y

la receiving antenna.

' l 19, such as heater voltages and plate voltage, are fedk to the magnetron 19 through theL plug 22. l Other components may also be mounted 20, such ,as `the transformer 23, -whichmay be used to supply anode voltage yto .the .magnetron 19. in addition, l

such items asy resistors tor .condensers, illustrated for es ample ext2-fl, may be appropriately-connected totterminals attached tothememberfzt).

The support member 20 is yresilientlyy attachedl to thel brackets .32 ,attached to the-horns 11. and'lZ and'to the The horn 11' is similar tothe horn 12 but is used'as Consequently, there is no coaxial line coupling themagnetron 1-9 with the receiving horn `11. '.lnstead, there isfillustratedherein 'a balanced mixer utilizing a pair tof crystalrectiiiers 33. positioned inholdvers 34, extending into the sides of the'receiver horn 11. This mixer section, 'which may lbe ot any desired well Lknown type, beats the iportionothe signal fed directly, l fromthe transmitter horn. 12 to `the :receiver horn 11,' in

a manner to be described presently, with reected echo signals to produce fanoutput :signal having ya llow frequency component, n ventional wiring to any desired utilization circuit, such as an indicator. yThe crystalsare fed out of phaseby the echo. signals received by the horn 11,y by the portion of the signal Yfromhorn' '12. The details of the mixer sectionfare more completelyy describedin copending application, Serial No, 212,932, filed vFebruary f l27, 1951, by Llenks yet' al, now? PatentNo. 2,713,636, dated July 19,1955.

on the member The metallic .cups 3G are, in turn, bolted by Ameans of bolts 33t to said component being fed over con# 1 l `wall portion andtin phase i l of the ground planeil'.l :Since y an appreciable `portion "of va quarter wave length fthicio the, junction of ground plane lllfwith the lip portion 49 ln orderl to feed the `desiredportion of the transmitted signal directly from the transmitting `horn 12 to the receiving horn 11, there is provided fa coaxial line having a central conductor 36. One .end of conductor 36 is connected to a coupling loop 57 extending into transmitter horn 12 through an aperture in the shorting plate 14 at the rear of horn 12. An insulating bushing 38 is provided around the portion `of loop 37 which passes through the shorting plate 14 vto insulate member `257 from the shorting plate at this point. The end of the loop 37 inside the horn 12 is connected to 'one Wall of the horn .12.

The other end of conductor 36 extends into the horn i signal passing from the transmitting horn through the coaxial line, whose central conductor is 36, to the receiv ing horn 11. The outer conductor of the coaxial line whose inner conductor is 36 comprises a rigid member made in two parts to facilitate Vassembly of the device. The lirst or lower'half 41-of the outer conductor is rigidly attached to the h'orns 11 land 12. The second half 4Z or cover is screwed, for example, by screws 43, to the member 41, therebyproducing a `completely rigid `coaxial line assembly connecting the 'transmitter `horn 12 with the receiving horn11.

The large `ends o'f ythe horns 11 and 12 are rigidly attached to the ground `plane 12 which has sufficient thicknessito prevent `any relative `movement between the large ends of the horns. The members 41 Iand 42 are also sutliciently 4.rigid to prevent any relative motion between the vsmall ends of the horns. -Thus it'may be seen that the transmitting and receiving horn structure is a rigid unit, thereby eliminatinggpossibility of yspurious signals due to variation of the distance-between the receiving and transmittinghorns.

member .44 ismade'such ln order to prevent dust and other material from. entering the horns 11' and12, y'the large ends of the horns are dielectric material 44 is permeable by radiated energy and the thickness of the as to provide the best impedance match between the horns'sand ,the'free space. ample, it has vbeen Afound that tor the particular horn contiguration illustrated, good 'results `may be obtained y with a member 44wh1ehnis '.approximately sixltenths'o a wore lengththiclc:at.thetlesiredxoperating Wave length ofthe system. y y

There is provided a `'cover '45' surrounding. the horns and associated structureand'engaging the ground plane tu. The coverii comprises aptessed `metal covering member 46 which is attached, for examplcgbyA riveting or spot welding, toa ring 47 surrounding the horns adjacent the ground planelb'. The ring,

example, a casting,'has yaslotul -tlterein whosedepth is l made on the order of a half iwaverlength -When-theecover is attached to thelgroundmlanetlo.' Thefslotld is filled with a dustprotectivemedium, such ,as cork, and.y rthe 49 ofthe fslot\48, which'isfpositioned'ncarest lthe ground plane Y19, has azcoikiwasher 5l) positioned in substantial Contact withusaid `Wall portion and the yground f .plane .'16 is attached to 'the'rin'g .51 extending .through the :ground plane 10, The lground t? by means of screws .plane 1G and threadedly engaging ,a nutsSlc attached to l ring '17, The `portronftn thering;4'7 which surrounds yground, plane :10, `isfspaced therefromrby ia portionofthe 'to the :support structure, for ex-l slot 48, and isv attached ample, `the skin 52 of an airplane, by means of rivets'53.'

Since thelsljot 48 .is `substantially aihalf wave length deep,

the bottom oftheslot, whichlis` shorted Aby the memberj `face of thel altreiiects a short circuit to the exterior system comprising ithezskin 152 and they exposed surface will be' at 'a relativelyl high liirnpe'dar'lce' point `along the slot IES. Accordingly, any xlooseness of the screws 51 will not cause a static :condition to Vbe generated by vibration of the ground plane and rhorn structure with respect to the ring member 47.

Referring now `to Fig. 5, there is `shown `a block diagram `of a frequency-modulatedor Doppler .radar device embodying the antenna system `illustrated in Figs. l, 2, and 3. There isshown schematically within the antenna system unit, indicated by the components within the box 5ft, transmitting and receiving horns .Land 11 connected to Va ground plane 1G. The transmitting `horn ,12 1is .fed kenergy from a transmitterSS, :which maybe, for example, `the magnetron 19, through ailirleS which consists of the necessary Wave ,guide `or coaxial line structure. The energy is radiated from the horn 12as at `57, and upon impinging on remoterobjects `is .reilected back to the horn 11 as at 58. A small `portion of energy `is also fed directly from the horn 12 tothe mixer receiver section S9 `attached to the horn 11 through line 69 fwhich may comprise, for example, the members 36, 40, 41, and '42, `illustrated in Figs. l through 3.

The imixer .receiver -sectionSQmay be, `for example, a balanced crystal mixer, as illustrated in Fig. l. The output of the mixer receiver section 59 :is an audio frequency which .isifedfbymeans ofxconventiorral `wiring 61 to fanlindicator 62, such as `a meterxorfcathode ray tube. A `power supply 63ris `provided Afor supplying power to the transmitter =ancl 'the indi'c'at'or by .means of conven- 'tionalwiring `Referring .now tto Fig. V6, "there is shown a 'modicavtion of the systemiillustrated'lin Fig. 4 to Aallow use of the systemwith a pulse -echo-radarfsy'stem. The system is :similai- 't'o Athat shown in Fig. 5 -except that the transmitter is pulsed l'instead"o'being a continuous `wave transmitter. There lis no Yline connecting the trans- For ex- 47'which may be, for

.the ground plane 10 isy niitter' horn lwith the receiver horn but rather a local oscillator 64 is provided for supplying a mixing signal to the mixer receiver section 59. Also, a synchronizing pulse is fed from the transmitter 55 to the indicator 62, by means of a line 65, to synchronize the indicating device 62, for example, the initiation of 'the sweep ofv a cathode ray tube with the emission of a pulse of highfrequency energy from the transmitter 55.

Referring now to Fig. 7, there is shown diagrammatically an installation of the antenna system 54 in a radar system, such as a marine naviga-tional radar, wherein the antenna system is adapted to rotate about a vertical axis. The antenna system S4 is fastened to a cylindrical support member 66, for example, in the same manner that it is illustrated as being fastened to the skin 52 of the airplane in Figs. l through 4. The -cylinder 66 has the axis thereof positioned vertically and is attached to a shaft 67 which rotates the cylinder 66 about its axis, thereby causing the antenna system 54 to scan in a horizontal direction about the vertical axis. The shaft 67 is supported by a gear box 68 through which a motor 69 drives the shaft 67 by means of gears which are not illustrated.

This completes the description of the embodiments of the invention illustrated herein. However, many modifications thereof may be made without departing from the spirit and scope of this invention. For example, a particular mounting of lthe antenna unit with respect to the support structure is shown by way of example only, and any desired mounting structure could be used. The crystal mixer structure and the probe for coupling the energy into the transmitting horn could have other well-known devices and structures substituted therefor. Accordingly, it is desired that this invention `be not limited by the particular details of the embodiments illustrated herein except as defined by the appended claims:

What is claimed is:

1. An antenna system comprising a plurality of fixed wave guides, one end of each of said wave guides regis- -tering with a separate aperture in a ground pl-ane and the other end of each of said wave guidesv being fixedly coupled to respectively different signal translation means, said apertures lbeing spaced along said ground plane by a plurality of Wave lengths at the operating frequency range of said system.

2. An yantenna system comprising a plurality of iixed wave guides, a ground plane, one end of each of said wave guides registering with a separate aperture in said ground plane and the other end of each of said wave guides being fixedly coupled to separate signal translation means, and a rigid member connected between said wave guides substantially at the points of coupling to said signal translation means.

3. An antenna Isystem comprising a plurality of xed wave guides, a ground plane, one end of each of said wave guides registering with a separa-te aperture in said ground plane and the other end of each of said wave guides being iixedly coupled to separate signal translation means, a source of sign-als mounted between said wave guides and fixedly coupled to one of said wave guides through one of said signal translation means, said apertures being spaced along said ground plane by a plurality of wave lengths at the operating frequency range of said system, and a rigid member connected between said wave guides substantially at the points of coupling to said signal Itranslation means.

4. An antenna system compri-sing a plurality of fixed Wave guides, a ground plane, one end of each of said wave guides registering with a separate aperture in said ground plane and the other end of each of said wave guides being iixedly coupled to respectively different sign-al translation means, and a rigid member connected between said wave guides at points remote from said ground plane, said rigid member comprising a signal translation channel between said wave guides.

5. An antenna system comprising a plurality of fixed wave guides, a ground plane, one end of each of said wave guides registering with a separate aperture in said ground plane and the other end of each of said wave guides being xedly coupled to separate signal translation means, and a rigid member connected between said wave guides at points remote yfrom said ground plane, said rigid member comprising an attenuating signal translation channel between said wave guides.

6. An antenna system comprising a plurality of fixed wave guides, a ground plane, one end of each of said wave guides containing a solid dielectric and registering with a separate aperture iny said ground plane, a surface of said dielectric being substantially flush with said ground plane, and the other end of each of said wave guides being iixedly coupled to respectively different signal translation means, a source of signals mounted between said wave guides and fixedly coupled to one of said Wave guides through one of said signal translation means, said apertures being spaced lalong said ground plane by a plurality of wave lengths at the operating frequency range of said system, and a rigid member connected between said wave guides substantially at the points of coupling to said ysignal translation means, said rigid member comprising an attenuating signal ltranslation channel between said wave guides.

7. An antenna system comprising a plurality of fixed wave guides, a ground plane, one end of each of said wave guides containing a solid dielectric and registering with a `separate aperture in said ground plane and the other end of each of said wave guides being fixedly coupled to separate signal translation means, and a rigid member connected between said wave guides at points remote from said ground plane, said rigid member comprising an attenuating signal translation channel between said Wave guides.

8. An antenna sys-tem comprising a plurality of fixed energy radiation horns having signal translation means coupled thereto, and means for isolating said horns from each other comprising a ground plane, the large ends of said horns containing a solid dielectric and being rigidly connected to said ground plane, a surface of said dielectric being substantially ush with said ground plane and the other end of each of said horns being fxedly coupled to respectively different signal translation means, a "source of signals mounted between said wave guides and fixedly coupled to one of said wave guides through one of said signal translation means, and a rigid member connected between said ho-rns at the small ends thereof, said rigid member comprising an attenuating signal translation channel between said horns. I v

9. An antenna system comprising a plurality of fixed wave guides, one end of each of said wave guides registering with a separate aperture in a ground plane and the other end of each of said wave guides being iixedly coupled to respectively different signal translation means, said guides being tapered in the regions of registry with said apertures in a direction perpendicular to a line intersecting the axes of said guides and being substantially straight in the region of coupling to said translation means, said apertures being spaced along said ground plane by a plurality of wave lengths at the operating frequency range of said system.

l0. An antenna system comprising a plurality of fixed wave guides, a ground plane, one end of each of said wave guides registering with a separate aperture in said ground plane and the other end of each of said wave guides being xedly coupled to separate signal translation means, said guides being tapered in the regions of registry with said apertures in a direction perpendicular to a line intersecting the axes of said guides and being substantially straight in the region of coupling to said translation means, and a rigid member connected between said wave guides substantially at the points ofcoupling to said signal translation means.

ll. An antenna system comprisinga plurality of xed wave guides, a ground plane, one end of each of said wave guides registering with a separate aperture in said ground plane and the other end of each of said Wave guides being coupled to separate signal translation means, said guides being tapered in the regions of registry with said apertures in a direction perpendicular to a line intersecting the axes of said guides and being substantially straight in the region of coupling to said translation means, a source of signals coupled to one of said wave guides through one of said signal translation means, said apertures being spaced along said ground plane by a plurality of wave lengths at the operating frequency range of said system, and a rigid member connected between said wave guides substantially at the points of coupling to said signal translation means.

12. An` antenna system comprising a plurality of fixed wave guides, a ground plane, one end of each of said wave guides registering with a separate aperture in said ground plane and the other end of each of said wave guides being xedly coupled to respectively different signal translation means, said guides being taperedA in the region of registry with said apertures in a direction perpendicular to a line intersecting the axes of said guides and being substantially straight in the region of coupling to said translation means, and a rigid member connected` between said wave guides at points remote from said ground plane, said rigid member comprising a signal translation channel between said wave guides.

13. An antenna system comprising a plurality oixed wave guides, a ground plane, one end of each of said` wave guides registering with a separate aperture in said ground plane and the other end of each of said wave guides being iiXedly coupled to separate signal transla.- tion means, said guides being tapered in the regions of registry with said apertures in a direction perpendicular to a line intersecting the axes of said guides and being substantially straight in the region of coupling to said translation means, and a rigid member connected between said wave guides at points remote from said ground plane,v

said rigid member comprising an attenuating signal translation channel between said wave guides.

14. An antenna system comprising a plurality of fixed wave guides, a ground plane, one end of each of said wave guides containing a solid dielectric impedance matching member registering with a separate aperture in said ground plane, a surface of said dielectric being substantially flush with said ground plane, and the other end of each of said wave guides being coupled to respectively ditferent signal translation means, said` guides being tapered in the regions of registry with said apertures inl a direction perpendicular to a line intersecting the axes of said guides and being substantially straight in the region oi coupling to said translation means,v a source Cil o f signals, coupled to one of said wave guides through one of said signal translation means, said apertures being spaced along said ground plane by a plurality of wave lengths at the, operating frequency range of said system, and a rigid member connected between said wave guides substantially at the points of coupling to said signal translation means, said rigid member comprising an attenuating signal translation channel between said wave guides.

15. An antenna system comprising a plurality of xed wave guides, a ground plane, one end of each of said Wave guides containing a solid` dielectric and registering with aseparate aperture in a ground plane and the other end of each of said wave guides being iixedly coupled to separate signal translation means, said guides being tapered in the regions of registry with said apertures in a direction perpendicular to a line intersecting the axes of said guides and being substantially straight in the region of coupling to said translationmeans, and a rigid member connected between saidwave guides at points remote from said ground plane, said rigid member comprising an attenuating signal translation channel between said wave guides.

16. An antenna system comprising a plurality of fixed energy` radiation horns having signal translation means coupled thereto, and means` for isolating said horns from each other comprising a ground plane, the large ends of said horns containing a. solid dielectric impedance matching member and being rigidly connected to said ground plane, a surface of said` dielectric being substantially flush with `said ground plane,` andj the other end of each of said horns beingiixedly coupled, to respectively different signal translationmeanasaid guides being tapered in the regions of; registry with; said apertures in a direction PQIPGDQCRMLILQ alinefintelseting the axes of said guides and being substantially straightinthe region of coupling to said translation means, a source ofl signalsV mounted between said wave guides and tixedly coupled to one of said wave guides through` one of said signal translation means, and a rigidrnernber connected between said horns at the small ends thereof, said rigid member comprising an attenuating signal` translation channel between said horns.

References Cited in the le of, this` patent Hammond et'l. m. Mar. 13, 1951 Riblet. et al. Apr. 10, 1951 

